Furnace wall



Dec. 19, 1933. E. G. BAILEY 1,939,650

' FURNACE WALL Filed Sept. 19, 1930 5 Sheets-Sheet 1 MIN/@NTOR BY fiWJlu d Y ATTORN EY Fl (5. a

Dec. 19, 1933- BAILEY 1,939,650

FURNACE WALL Filed Sept. 19. 1930 5 Sheets-Sheet 2 I ENTOR FIGZ, W W

ATTOR N EYJ FURNACE WALL- Fneds e t. 19. 1930 5 Sheets-Sheet 3 w INVENTOR L I BY M W ATTORN EYS Dec. 19, 1933. BAILEY 1,939,650

FURNACE WALL Filed Sept; 19, 1950 5 Sheets-Sheet 4 VENTOR Flas. F

D86. 19, 1933. E G. BAlLEY FURNACE WALL Filed Sept. 19. 1950 5 Sheets-Sheet 5 FIG.8.

i IN%ENT OR 7 BY j I MW ATTORN EY Patented Dec. 19, 1933 1,939,650 FURNACE WALL Ervin G. Bailey, Easton, Pa., assignor to Fuller Lehigh Company, Fullerton, Pa., a corporation of- Delaware Application September 19, 1930 Serial No. 482,937

2 Claims. (Cl. 1226).

This invention relates to a furnace wall that is provided with water cooling tubes to which blocks or tile are connected, the blocks or tile having air ports through which secondary air may enter the furnace. A casing is located outside of the wall and spaced therefrom, leaving a space through which the air first passes before entering the furnace. This space may be divided into parallel air passages. The invention is especially useful in connection with a powdered fuel furnace into which the powdered fuel is introduced in a downward direction near the water cooled wall.

The invention will be understood from the'description in connection with the accompanying drawings, in which Fig. 1 is a vertical section through an illustrative embodiment of the invention; Fig. 2 is a front view partly in section; Fig. '3 is a section on an enlarged scale showing some of the details; Fig. 4 is a section along the line 4-4 of Fig. 3; Fig. 5 is a section along the line 5-5 of Fig. 3; and Fig. 6 is a vertical section similar to Fig. 1, partly broken away, showing a modification; Fig. 7 is a section along the line 7--7 of Fig. 6; Fig. 8 is a section along the line 8-8 of Fig. 6, and Figs. 9, 10 and 11 are sections through different parts of wall blocks.

In the drawings, reference character 1 indicates a furnace, above which a boiler 2 of the Babcock & Wilcox type may be located. This boiler is provided with the usual steam and water drum 3 and an ash hopper 4 is provided at the lower end of the furnace 1. One or more burners 5 may be located-in position to introduce fuel into the furnace through a horizontally disposed arch so that the fuel will enter the furnace in a downward direction. Auxiliary burners 5 may be used to introduce fuel into the lower portion of the furnace in a horizontal direction. The hot products of combustion pass upwardly across the heating surfaces of the boiler 2.

The front'wall of the furnace is provided with a row of vertically disposed tubes 6. The lower ends of thetubes 6 enter the horizontally disposed header 7 and the upper ends of these tubes enter a horizontally disposed header 8.- Recirculating tubes 9 outside of the furnace wall connect the headers 7 and 8. One or more tubes 10 connect the water space of the steam and water drum 3 to the header 7 and tubes 11 connect the header 8 to the steam space of the steam and water drum 3, so that boiler water circulates througf... the row of tubes 6.

The boiler casing 12, which may be made of metal and air tight, is spaced from the tubes 6, thus forming a hollow wall with a chamber 13 into which secondary air passes before entering the furnace. The chamber 13 may be provided with partitions 14 to provide air channels that ay be horizontal or may extend in other direcions. The casing 12 may be provided with access doors and air ports 15 which may be used to permit air to enter the chamber 13 directly from the boiler room.

There are blocks or tile mounted upon the furnace wall tubes with ports or openings therethrough to permit air to enter the fumaceat different places through the walls; For this purpose, the tubes 6 are shown lined with blocks or tile some of which areindicated as being made in sections 16 and 17 on opposite sides of the plane through the center lines of the tubes 6, although it is not necessary to make the blocks in sections as single sections may be used. The sections 16 and. 17 forming a block are clamped to the tubes 6 by means of the bolts 18 that pass through the sections 17 and are screwed into the sections 16 with nuts 19 on the bolts to tighten the sections against the tubes. At intervals along the furnace wall may be placed blocks formed of sections 16 and 17 which are provided with aligned openings 20 for the passage of air from the space 13 into the furnace 1. The sections 16 and 17 are provided with curved surfaces 21 to flt the outside of the tubes 6 and provide good thermal contact therewith. Some of the bolts 18 are elongated as indicated at 22and radiant heat shields 23 are mounted on these 810111- gations in front of the openings 20 so as to prevent escape of radiant heat from the furnace. The shields 23 are provided with curved surfaces 24 on the furnace side to make provision for the passage of combustion air from the space through the openings 20 into the furnace.

As many of the blocks or tile that are provided with air openings are installed on the tubes 6 as are desired, the remainder of the blocks or tile on these tubes being solid or continuous. By having the blocks removable and replaceable, the number and location of openings through the wall canbe varied to suit conditions.

The burners 5 and -5' are preferably of a type that injects a relatively small percentage of air with the fuel in such a way that a somewhat long and lazy flame is produced as contrasted with a turbulent type of burner. The secondary or additional air that is required for combustion purposes is admitted into the furnace near the flames through the front wall of the furnace. For this purpose, the front wall of the furnace is provided with air ports which not only permit the secondary air to be injected or admitted into the furnace in proper relation to the flame, but also provide a wall structure that will withstand the intense heat near the-flame but will not be so cold that it will hinder proper ignition and combustion. I

In order to keep the wall of the furnace at the proper temperature, furnace wall blocks of different types which have different rates of heat absorption, are located at different portions of the furnace wall or walls in vertical planes. For example, furnace wall blocks of low heat conductivity, which will, therefore, assume a high temperature, are located near the fuel burners, so that fuel will be quickly ignited as it enters the furnace, the furnace wall blocks of high heat conductivity are located farther away from the fuel entrance, and blocks of still better heat conductivity may be located at other portions of the furnace.

In order to supply preheated combustion air through the front wall of the furnace, an air duct 25 leads air to a manifold 26. The space between the boiler casing and the furnace may be divided into horizontal lanes as, for example, by means of partitions 14 mentioned above, and the entrances to these horizontal lanes from the manifold 26 are controlled by dampers 2'7 that may be independently regulated to permit different amounts of air to pass through the different lanes, if desired. The air passing through these lanes becomes heated before it enters the furnace through the ports in the front wall of the furnace.

In the modification shown in Figs. 6 to 8, the same reference characters are used to indicate the parts that correspond to those in Fig. 1.' In this modification, the arch 28 at the upper end of the front wall is provided with water cooling tubes 29 that are bent near the burners 5 to provide larger spaces for entry of the fuel. The tubes 29 extend from the header 8 into the horizontally disposed header 30 that is connected by means of the recirculating tubes 9 to the lower header 7. The tubes 29 and arch 28 may be supported by spring supports as indicated at 31 and the sides of the furnace may also be provided with water cooling tubes as indicated some what diagrammatically at 32.

In the illustrative embodiment of the invention shown in Fig. 1, the arch through which the burners 5 project the fuel is made of refractory material which becomes highly heated, so that there is a high temperature at the point where the fuel enters.

In the modification illustrated in Fig. 6, the arch is water cooled by means of the tubes 29 and blocks or tile of different heat conductivity are attached to different portions of these tubes 29. Blocks 33 may be applied along the horizontal portion of the arch 28, which blocks are faced with refractory material of low heat conductivity, so that these faces will become very hot to maintain sufficiently high temperature for proper ignition of the fuel as it enters the furnace. One of these blocks is shown more in detail in Fig. 9 in which the reference character 34 indicates the metallic portion of the block that is provided with curved surface to fit against the tube 29. The face of the block is provided with refractof'tr material 35 which remains at a high temperature during the operation of the furnace.

The upper portions of the tubes 29 may be lined with bare metal blocks 36, one of which is shown in-Fig. 10. These blocks have high heat conductivity and, therefore, remain relatively cool, so that there will be no accumulation of ash or slag on them which would break off in large masses and fall to the bottom of the furnace.

Other portions of the furnace walls may be lined with refractory blocks of the sort indicated in Fig. 11 by reference character 37, in which the metal portion thereof is provided with curved surfaces to fit against the tubes 29, the fiat face of the metal being provided with shallow recesses 38 in which slag will collect, thereby providing a heat insulating material on the face of the blocks to make the same of a degree of heat conductivity intermediate the blocks shown in Figs. 9 and 10. r

In the modification shown in Fig. 6, the blocks along the furnace walls are arranged so as to gradually increase the rate of heat transfer from the top of the wall to the bottom, thus cooling the flame to its lowest temperature at a point at the bottom of the wall where it changes direction and starts to sweep rearwardly and upwardly to the boiler. Refractory faced blocks should therefore be used along the upper portion of the vertical wall. A zone of rough faced blocks with higher heat conductivity should be used lower down and bare metal blocks of highest heat conductivity should be used at the bottom to avoid excessive collection of slag in the zone adjacent the lower wall that is usually made of brick.

In a furnace such as that shown in Fig. 1, where both vertical and horizontal burners are provided, rough faced blocks should be used along the upper portion of the wall near the vertical burners 5 and the arch through which these burners project fuel in order to keep the wall from slagging excessively and closing up the air ports. In the zone below these blocks where the flame from burners 5 turns toward the center of the furnace and the temperature mayv trickle down and close up the openings for them.

In the modification shown in Fig, 6, the air duct 39 leads to a manifold 40 near one edge of the front wall of the furnace and dampers 41 are provided for admitting air from this manifold into the several air channels along the front wall of the furnace. These dampers 41 may be operated by the operating mechanism 42 to control the amount of air entering the air channels between the casing and the furnace wall.

I claim:

1. In a furnace wall comprising a row of spaced cooling tubes and blocks removably secured thereto, means forming an air chamber-on the outer side of said wall, one of said blocks having an opening therethrough to permit fiow of air into the furnace from said chamber, a shield on the block on the outer side of the row and arranged to extend over said opening to prevent the passage of radiant heat while permitting said flow of air through the opening, and'means detachably holding said shield and block together.

2. A furnace wall comprising spaced cooling tubes and blocks secured thereto and having openings therethrough to permit flow of air into the furnace, means forming an air chamber on the outer side of said wall, shields on the blocks on the outer side of the wall and arranged to extend over said openings to prevent the passage of radiant heat while permitting said flow of air through the openings, and means for detachably securing said shields in position whereby they may be exchangeably arranged over selected ones of said openings.

' ERVIN G. BAILEY. 

